Various types of heater members for heating a heat subject placed thereon have been conventionally proposed. For the purpose of heating semiconductor wafers, liquid crystal panel substrates, and others for processing, exemplified is a heater member mainly made of ceramic including aluminum nitride that provides high heat conductivity and high heat uniformity, or aluminum oxide that is low in price or others. As to such a heater member, various studies have been conducted with respect to its shape, structure, or the like, to achieve effective heating of heat subjects.
As a specific example of such a conventional heater member mainly made of ceramic-based material, as shown in FIG. 1, there is a heater member for use in a heat processor such as a semiconductor wafer. This heater member 1 is structured by a heater substrate 2 in which a ceramic base 4 is provided with a heat-generating wiring section 3, and a tubular support body 5 made of ceramic or others, and including a feed wiring configuration 6 electrically connected to the heat-generating wiring section 3, a thermocouple 7 for a heater temperature monitor, and the like. The heat-generating wiring section 3 provided to the heat substrate 2 is made of a conductive material exemplified by tungsten shaped to be substantially spiral.
The heat processor such as a semiconductor wafer carries the heater member 1 in a cabinet 8, and a heat subject 9 such as a semiconductor wafer is placed on the heat-subject-placing surface of the heater substrate 2 for various processing such as film formation, etching, or others during heat application. The issue here is that due to the recent fact that wafers have been increased in diameter, and semiconductor chips to be formed to such wafers have been reduced in size, for example, the heater member 1 is required to perform heat application with high accuracy, and the heat-subject-placing surface of the heater substrate 2 is required to be uniform in temperature to a greater degree. Moreover, for energy conservation purposes, the heating efficiency also is required to be increased.
As a measure taken thereto, a method is exemplarily proposed in JP-A-7-307258 to derive the uniformity for the inner surface temperature of a wafer during a heat process by placing a disk-shaped temperature compensation member in a manner such as to sandwich the wafer prior to the heat process. Moreover, in JP-A-2002-313890, a method is disclosed to heat a heat subject such as a wafer in an efficient manner by reducing the amount of heat coming from the heater member toward the outside with such a structure in which the surface(s) not including the heat-subject-placing surface is at least partially mirror finished.